Subaru WRX & STi

How to tune a Subaru WRX or STi without a dyno

Usually, to get the most power out of your Subaru WRX or Subaru Impreza STi, you need to take your car to a professional tuner with a dyno. The tuner would tune your car to make the most power and torque while still making sure your engine has plenty of fuel and just the right about of timing to keep everything safe under the hood. While we’re not saying you shouldn’t take your car to a tuner, we want you to know of an incredible alternative to tune your WRX or STi by yourself, and have the ability to continuously monitor all your vitals from one easy to use handheld system. Introducing the COBB AccessPORT!

What’s the COBB AccessPORT?
Technology has come a long way, and COBB Tuning has created an awesome product called the AccessPORT. Simply put, it’s one of the most powerful and easy to use hand held tuner available for the WRX or STi. This unit flashes your ECU and reports on all vitals to ensure your car is running safe while making plenty more power. COBB even includes pre-installed maps that are optimized for common performance modifications such as cold air intakes, exhaust systems, higher boost and more. The best part is if for any reason you want to return back to stock, it’s as easy as pushing a few buttons and restoring all factory settings. It can’t get any easier, and with the incredible performance increases we love this tuner and highly recommend it.

The COBB AccessPORT is available for these WRX and STi years:

COBB AccessPORT Subaru WRX (02-05) AP-SUB-001
COBB AccessPORT Subaru WRX (06-07) AP-SUB-002
COBB AccessPORT Subaru WRX/STI (08-12) AP-SUB-003
COBB AccessPORT Subaru Impreza STi (04-07) AP-SUB-002

How do you install the COBB AccessPORT?
Incredibly easy to install… and requires no tools, no wiring and no custom work. Simply plug the unit into your car’s OBD-II port and follow the easy instructions on the screen of the AccessPORT. The unit guides you through the install process and within minutes your car will be tuned with additional power and better drive-ability. Works great on a completely stock car to a fully modded car.

What kinds of maps are available?
Changing maps is as easy as pushing a few buttons. You can store 100 different maps with the AccessPORT. For example, if you are going on a long trip, you can select the fuel economy map and get the best possible fuel economy. If you are leaving your WRX or STi somewhere overnight, you can load the anti-theft map and keep your car from being able to start! Leaving your car with the valet at a restaurant or hotel? Load the valet map to limit the performance of your car! These are simply incredible, and only a few examples of why we love the AccessPORT!

You would wouldn’t have enough room in your car for an individual gauge of everything the AccessPORT can monitor. With the AccessPORT you can monitor your engine vitals and datalog them so you can review them later by plugging your AccessPORT into a PC or Mac and reviewing it on your favorite spreadsheet. Some available gauges are:

  • Throttle Position
  • Boost
  • Ignition Advance
  • Wastegate Duty Cycle
  • Mass Air Flow
  • Intake Temperature
  • Air/Fuel Ratio
  • Calculated Engine Load

Clear your check engine lights and trouble codes
Modified your car and now have a check engine light? Even if your car is stock and you have a check engine light, the COBB AccessPORT reads your trouble codes so you can diagnose and fix the issue. You can also clear the codes using the unit and remove the check engine light.

I have intake and exhaust, how much power can I gain with the AccessPORT?
Horsepower and torque gains vary from vehicle to vehicle due to different setups, altitude, temperature, and other conditions, but in the past we have seen a stock WRX or STi gain as much as 20 horsepower, and a modified WRX or STi gain as much as 45! The COBB AccessPORT checks to see where it can make changes to improve power. For example, if you added an intake and exhaust, and it caused your car to run rich, the AccessPORT will lean the fuel mixture to safe levels so your car will make drastically more power, improve fuel economy and run smoother.

Launch your WRX or STI harder than ever before
If you are about to launch your car, you push your clutch down and feather the gas to the perfect RPM. The problem is that the ECU limits how much your car can rev in this situation, so you can’t get a hard launch. With the AccessPORT you can set what RPM you want your car to launch at. If you set 5000 RPM, all you need to do is press your clutch down, and floor the gas. The RPMs will shoot up to 5000, and you can drop the clutch to give you neck snapping launches!

Do I need a new ECU?
The great thing about the COBB is that it works with your stock ECU. Subaru spent an incredible amount of time and effort to develop the complex ECU to manage all aspects of your WRX or STI. What the AccessPORT does is simply tweeks the signals to and from the ECU to alter how it manages your engine. A stock ECU is designed to be overly safe, at the expense of extra power. COBB unlocks this, while still maintaining a safe cushion so you can expect more power without more risk.

What kinds of modifications do you recommend?
The beauty of the WRX and STi is that they are both turbo engines that are just waiting to be opened up to create power. We recommend basic mods to start such as a short ram intake or a cold air intake. Once you have more air flow coming in, you need to give your car an easier way to get it out. We recommend a full exhaust system. With these mods and a COBB AccessPORT our customers have gained over 50 horsepower and just as much torque! Your car will sound better, drive smoother, and make tons more power with only three modifications!

We recommend that if your car is stock to start with the COBB AccessPORT. You will get a good baseline performance increase, and you can take your car to the dyno before and after to see how much power it gained. You can then easily justify each modification you do after and will already have a way to tune after each one.

What else do I need to tune my car?
Everyone’s car is different, and some people might need extra parts to get the most from their AccessPORT. For example, if you have a larger turbo, you might need larger injectors depending on how much boost you are running, and since you are literally running out of fuel, the AccessPORT can’t help until the fuel is there. For similar situations, we highly recommend visiting a tuner.


  1. The COBB also Works on Subaru Impreza gt my00???

  2. Hi i have a jdm grb sti on my country we used 94 ron fuel can i used acess port ?cobb?

  3. Really a short ram intake? You know nothing about tuning a WRX or STI. Do yourself a favor and read a real article on tuning.

  4. Im putting a TDO5/TDO5H 18G turbo in my 2003 WRX would the COBB help put this all together with my other mods?

  5. Anthony you would have to get it tuned by a tuner that uses a cobb accessport. You basically buy the accessport and download maps from the cobb website. There is usually a text file or pdf file that tells you what exact mods you need to run that specific map. For me the accessport was convienent for switching maps. Most of the maps are not really useful because some people have different mods or plans and there are not much maps to choose from. You also have a choice of romraider which is opensource tuning.

  6. Can you tune a Subaru 2002 RS?

  7. Hi,
    Can this Cobb access port work on Gvf models and also can this also work on tropical country like Philippines hot and humid ?

  8. you want to blow your engine having issues tune your car with this shitty gadget that worth the same price if not more then a real professional tune stupid article pretty sure they’re sponsor by COBB crappy gadget !!!

  9. I know cobb accessport isnt supposed to be ran with a catless downpipe but will the accessport on a stage 2 tune make the air fuel ratio rich out so the engine isn’t running to lean?

  10. I have a JDM Subaru. Is it possible to tune with COBB?

  11. Got the invidia uppipe. The rest i went cheap stainless steel .On my wrx 2013 .one of the last in Australia labelled Rs40 wrx. Only 300 built .Kn filter and tuned properly. With 18 pounds boost. By a proffesional. .We get 98%fuel hi octane here.And i can run a 12.2 anyday of the week. .just love watching these GTs commodores with there supercharged 6.2 litre corvette motors .Jaws drop. Lol. I really think anymore mods would ruin it.
    Take my advice go to a good tuner. It costs a bit but worth it … stay cool

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